Machine for forming concrete pipes



July 10, 1951 F. L. FITZPATRICK 2,560,426

MACHINE FOR FORMING CONCRETE PIPES 1 Filed July 20, 1948 INVENTOR.

Patented July 10, 1951 MACHINE FOR FORMING CONCRETE PIPES Frank L. Fitzpatrick, East Malvern, Victoria,

. Australia Application July 20, 1948, Serial No. 39,605

14 Claims.

My invention relates to means for forming pipes or other cylindrical bodies of concrete or like material, and more particularly to apparatus in which the concrete is compressed between a roller and a mold. According to previous practice, the most accepted method for fabricating concrete pipes of high quality has been the so-called centrifugal one. This method involves .the rotation of the pipe mold at a high speedsuch as 1500 to 2500 feet per minute peripheral velocitythe mold being held in rings or runners which are supported on and rotated by Wheels or trunnions. In order that the spreading of the concrete may respond rapidly to the speed of the mold, the above method requires that the mix be rather loose and wet.

The method referred to has a number of disadvantages. Thus, the necessary high speed of the mold and its running gear develops heavy wear and tear. Further, a machine constituted to operate as described must be of very stout construction and carefully balanced. Further, the relatively high water content of the concrete mix is prejudicial to its required strength and density; and the incidental dispersion of the water from the mix tends to form capillaries and ducts within the concrete mass. Further, during the rotation of the mix the coarser particles move to the outer portion of the pipe mass, while slurry and fines tend to collect on the inner side thereof and eventually run down and accumulate on floors and around the machine. Finally, a plant capable of producing the larger sizes of pipe becomes a project of a formidable character when constructed along the principle considered above, involving high costs.

With the above deficiencies of existing equipment in mind, it is one object of the present invention to produce a pipe forming machine which operates at a relatively low speed, and at the same time permits a concrete mix with a relatively low water ratio to be usedwith the advantage of a superior resulting product.

A further object is to include means in the novel machine whereby the concrete is compressed to a high degree of density, enabling the production of pipes or other cylindrical bodies economically superior in strength and water-tightness to those produced by the centrifugal or other previously known processes.

A still further object is to provide a machine of the above character which is of exceeding simplicity, economical to fabricate and. easy to operate.

An additional object is to construct a machine with features which are advantageous for the fabrication of large pipes or hollow cylindrical bodies, such as 24 inches and over in diameter.

With the above objects in view, a better understanding of the invention may be gained by reference to the accompanying drawing, which shows one application of the invention and in which Fig. 1 is a front end View of a machine constituted to produce work of conventional sizes;

Fig. 2 is a side elevation;

Fig. 3 is a section on the line'3-3 of Fig. 2;

Fig. 4 is a section on the line 4 4 of Fig. 1; and

Fig. 5 is a view similar to Fig. 4, showing a modification.

In accordance with theforegoing, specific ref erence to the drawing indicates that the mold I is of the normal type used in the manufacture of concrete pipes. It is made from a metal plate flexed to form a tube, the meeting flanges la thereof being secured by bolts lb. -Thus, when these are removed, it is possible to open the mold out and release the pipe made therein. Thickness rings 2, normally made of iron or steel, are secured within the mold. These rings assist to maintain the circular shape of the mold to determine the thickness of the wall of the pipe to be formed within the mold. In the present construction, the thickness rings 2 rest on a horizontal roller 3 and thus support the mold. The roller may be formed of shafting, tubing or the like. It is supported by bearings 6, l and 8, these being carried by floor standards ill. The bearing 6 is remov able, so that the mold with the finished pipe enclosed within it can be drawn off the roller, and a new mold placed in position. During the formation of the pipe, the roller 3 carries the weight of the mold and of the concrete contained therein. The mold is rotatable by a belt 4 driven from a suitable power source, the belt making frictional contact with the outer surface of the mold and thuscausing the latter to rotate. In order to maintain the necessary grip upon the mold an idler pulley 5 is provided which is capable of being adjusted to various positions (as, for example to the position 5a indicated by dotted lines), so that molds of various sizes can be used and the correct tension imparted to the belt. The bearings I andB are capable of supporting the roller in cantilever fashion when the bearing 6 is removed temporarily. Metal ribs 9 act as stif feners to assist in maintaining the mold in true circular shape, and also serve as guides to keep the belt in correct position with respect to the mold. The bearings 6, I and 8 and the supports ID are designed as open frames, so that adequate access is afforded into the ends of the mold for depositing the concrete therein.

In the formation of a pipe or like hollow article, the procedure is as follows:

The mold, with the reinforcement for the pipe or like hollow article (if reinforcement is to be used) in position, is assembled with the thickness rings firmly secured in correct position. The bearing 6 and its support are swung clear of the roller and the mold is carried to a position where it surrounds the roller (but does not rest on it) while held suspended from a suitable overhead support (not shown) The bearing 6 is then swung back into position to support the free end of the roller, and the bearing standard is then made fast. The mold is next lowered until it rests with its thickness rings upon the roller and is free to rotate. The belt is then tensioned suitably, so as to make the desired frictional contact with the mold, by moving the idler pulley to an appropriate position and fixing it there. When the belt is driven, it rotates the mold, the friction of the latter with the roller incidentally inducing the rotation of the roller.

The speed of rotation of the mold depends to some extent on the nature of the mold and on the .size and wall thickness of the pipe or like article which is being constructed, but a peripheral speed of about 800 feet per minute has been found suitable for a pipe which is 24 inches in diameter and has a 2-inch wall, and a peripheral speed of about 1000 feet per minute is normally suitable for a pipe which is 36 inches in diameter.

With this means of forming pipes and the like, concrete of low water content is suitable; for example, a concrete of 5 to 7 /2% Water total weight of aggregates and cement is suitable for a mix of 5 parts aggregate to 1 part of Portland cement. The concrete is introduced gradually, care being taken to distribute it well throughout the length of the mold. It follows now, with the mass of concrete in the bottom of the mold, that the rotation of the latter will carry more or less of the concrete around with the tendency of distributing the same along the inside of the mold wall. This action will be aided by the roller 3 which also presses or packs the concrete to the thickness limited by the space between the roller and the mold wall above the same. The result is therefore the formation of a concrete pipe of even thickness within the mold. When the pipe has been so formed rotation of the mold is stopped. The mold then is lifted just clear of the roller, the bearing 6 is swung clear and the mold is removed from the machine. It is then desirable to sleek off the inner surface of the pipe or like article with a knife or trowel to the required smoothness.

Fig. 4 shows that the thickness rings 2 are peripherally grooved at H to receive beads 12 pressed inwardly from the mold, locking the rings 2 to the mold. The roller 3 also carries collars l3 which serve as end-stops for the mold rings 2.

Fig. 5 shows a modification of the apparatus. When the pipe has been formed it is desirable in some cases to space it on the inside from the roller 3. This enables the inner surface to be troweled and smoothed during rotation, without interference or damage by the roller. This is done by raising the pipe, and using collars [4 formed with hubs [5 on the inner side, and lowering the mold to ride on the hubs I5. Now a clearance 16 is formed between the roller 3 and the internal surface of the mold.

The horizontal support for the mold, while preferably a freely rotatable roller, may be a fixed or non-rotatable support of cylindrical or part-cylindrical section. In the latter case the upper surface would be the rounded one.

In conclusion, it will be apparent that some advantages of the novel machine are that no high speed rotation is necessary as in the ordinary centrifugal process; the plant is of low cost and minimum complexity; there is very low wear and tear of the plant; and the maintenance costs are low. Further advantages are that very dense compacting of the concrete is obtained owing to the weight of the pipe and of the mold bearing upon the concrete as it passes over the roller, and the packing effect of the latter, so that pipes of exceptional strength and water-tightness are obtained. Less labor is required because no running rings have to be attached and dismantled each time a pipe is made, as is the case with pipes made by the older centrifugal process.

I claim:

1. A mold for forming pipes of concrete or other moldable material consisting of solid particles and a cementing agent comprising in cornbination, a hollow rotary receptacle for the material, a roller support for supporting the receptacle, said support being eccentrically spaced from the hollow rotary receptacle to define a minimum space between the receptacle and the support through which space the material is carried and compressed between the receptacle and its support, the weight of the receptacle and concrete or other moldable material being carried solely by the roller support and the weight thereof in addition to centrifugal action tending to compress the other moldable material, and means engaging the receptacle for rotating the same.

2. The structure of claim 1, and means to fix said minimum space.

3. The structure of claim 1, said receptacle being a cylinder and the support a freely rotatable roller axially parallel to the cylinder.

4. The structure of claim 1, said receptacle being a cylinder and the support a freely rotatable roller axially parallel to the cylinder, and means determining said zone comprising a transverse ring extended from the internal wall of the cylinder to meet said roller.

5. The structure of claim 1, said receptacle being a horizontally disposed cylinder and the support a freely rotatable roller axially parallel to the cylinder, terminal bearings for the roller, and frames forming supports for said bearings, said frames being open for access to deposit the material into the cylinder.

6. The structure of claim 1, said receptacle being a cylinder, and means for fixing said minimum space comprising a ring in each end of the cylinder and of a thickness corresponding to said minimum space.

7. The structure of claim 1, said receptacle being a cylinder, means for fixing said minimum space comprising a ring in each end of the cylinder and of a thickness corresponding to said minimum space, and means to lock the rings from departure endwise of the cylinder.

8. Th structure of claim 1, said receptacle being a cylinder, and means for fixing said minimum space comprising a ring in each end of the cylinder and of a thickness corresponding to said minimum space, each ring being formed with an annular groove in its periphery, and an inward bead formed from the related end portion of the cylinder, said bead seating in the groove to lock the ring from departure endwise of the cylinder.

9. The structure of claim 1, said receptacle being a horizontally disposed cylinder, and external means for supporting the same.

10. The structure of claim 1, said receptacle being a, horizontally disposed cylinder, and external means for rotating the same about its axis.

11. The structure of claim 1, said receptacle being a horizontally disposed cylinder, and external means frictionally engageable with the periphery of the cylinder to rotate the latter about its axis.

12. The structure of claim 1., said receptacle being a horizontally disposed cylinder and the support a freely rotatable roller axially parallel to the cylinder and supported closest to the top of the cylinder, and means frictionally engageable with the periphery of the cylinder to rotate the same, said means being adjustable to raise the cylinder in relation to said roller.

13. The structure of claim 1, said receptacle being a horizontally disposed cylinder and the support a roller axially parallel to the cylinder,

bearings for the roller endwise of the cylinder, and supplemental means for holding the roller in position in case one of said bearings is removed.

14. The structure of claim 1, said receptacle being a horizontally disposed cylinder and the support a roller axially parallel to the cylinder, bearings for the roller endwise of the cylinder, and supplemental means for holding the roller in position in case one of said bearings is removed, said suppemental means comprising an additional bearing spaced outwardly from the other of said bearings and furnishing a cantilever support for the roller in the event of said removal.

FRANK L. FITZPATRICK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

